译文：
气力输送是以压缩气源为输送动力,将粉状物料在密闭容器中从一端输送到另外一端。气力输送所应用的行业非常广泛,如电厂的煤粉、粉煤灰和炉底渣,化工行业的化工原料,建筑行业的水泥和石灰,食品医药卫生等行业的各种粉料或颗粒物料等。而各种阀门的合理选用在气力输送中是至关重要的。阀门要满足各行业气力输送的需求,应具有耐温、耐腐蚀和耐磨损等各方面的优良性能。 2、阀门分类 典型的正压气力输送系统如图1所示。根据阀门在系统中的位置及作用,分为进料用阀、排气用阀、进气用阀、出料用阀和切换用阀等。 2.1、进料用阀 进料用阀在气力输送中是用来切断和接通物料从输送点至输送容器的阀门。合理选择进料阀的口径决定了物料的流量以及整个系统的输送能力。根据输送介质的不同,对其耐温、耐腐蚀和耐磨性能也有不同程度的要求。根据经验,在不同的系统中通常选择闸阀、球阀、圆顶阀等作为进料用阀。 2.2、排气用阀 排气用阀是当气力输送系统进料时,将输送系统内的空气排到进料仓或者烟道中的阀门,以便于顺畅下料,缩短进料时间。其主要输送介质是带有少量粉状物料的空气。常用的排气阀有闸阀、蝶阀、夹管阀、球阀以及圆顶阀等。 2.3、进气用阀 常作进气用阀有蝶阀、球阀、角座阀等。进气用阀的输送介质为压缩空气,所以对耐磨蚀性要求不高。 2.4、出料用阀 当输送设备充满物料后,开启进气阀和出料阀,让物料在压缩空气的驱动下在输送管道系统内输送。所以出料阀的介质为混有压缩空气的粉状物料。作为出料阀的阀门一般有闸阀、球阀、圆顶阀等。 2.5、分路用阀 分路阀可以起到分流和汇流的作用,将物料从多点汇集到一点或者将物料从一点分散到多点。作为分路阀的有球阀、蝶阀或组合阀等,也有各厂家自制的分路阀。分路阀既可用于管路安装,也可用于库顶安装。一般用于库顶安装时,阀门入口需要连接弯头,库顶需装个小型的卸灰仓,以适当扩大物料通道,减少灰库扬尘。 3、阀门性能 3.1、闸阀 闸阀(图2)有两个闸板来切断物料,闸板的材料可选用不锈钢或合金钢等,以适用于耐腐蚀和耐磨损等工况。闸阀有手动、气动和电动3种操作方式。通常选用气动或者电动两种自动控制方式。但是由于其结构的原因,闸板的行程较长,对气动或者电动装置的扭矩要求大,动作周期较长,使用不够灵活。气动闸阀是在气缸的带动下闸板开启或关闭阀门,丁字形闸板座采用特殊结构,在带动闸板直线运动的同时沿中心作圆周转动,对阀座密封面起到了一定的自研磨以及抛光清洁作用,从而使密封闸板圆周均匀承受物料的冲击和磨损,避免了闸板在长期运行过程中局部损坏或磨穿,使其寿命大大延长。同时,双闸板在弹簧静压下能保证两面密封不渗漏,当闸板的一面有压力时,另一面通过弹簧的作用能和密封座更紧密的接触,以达到密封的效果。该阀在使用中的主要问题是密封及闸板的冲刷损坏。该阀适合于在全开或全关的状态下工作,如果闸板长期处于半开关的状态下工作,闸板的密封面会因受介质冲刷而变得不严密。因此该阀门在耐冲刷以及耐磨损方面还应进一步改进。 3.2球阀 球阀(图3)通常是选用自动(气动或电动)控制球阀。球阀有软密封和硬密封2种。软密封球阀的阀座密封圈材料是聚四氟乙烯,其具有摩擦系数小,性能稳定,不易老化和密封性能优良的特点。因为聚四氟乙烯具有较高的膨胀系数、对冷流的敏感性和不良的热传导性,当密封材料变硬时,密封的可靠性就受到影响。而且,聚四氟乙烯的耐温等级较低,只能在小于180℃情况下使用。超过此温度,密封材料就会软化。当长期使用时,温度一般应控制在120℃以下。 硬密封球阀作为进料阀一般用于介质温度较高的电厂除灰系统,由于气力输送系统通常24h连续工作,阀门动作频率比较高,一般几分钟,短的甚至几十秒钟就会动作一次。如果硬密封球阀的使用寿命为2～3万次,假设在气力输送系统中,阀门5min动作一次,那么球阀的使用寿命为70～104天,阀门的使用寿命较短。因此,在电厂除灰系统中,需要使用寿命更长的硬密封球阀。 3.3、圆顶阀 圆顶阀(图4)由于其结构的特殊性,通常是气力输送中的{sx}阀门。圆顶阀的壳体与穹形阀瓣材料常选用球墨铸铁、不锈钢、特种耐磨材料和钢衬氟塑料。密封圈材料常选用氯丁橡胶、硅酮橡胶、氟橡胶和三元乙丙橡胶等。圆顶阀是依靠压缩空气实现紧密密封效果的特殊阀门,适用于处理含尘气体、冲蚀性散装物料,如用于库/仓的放料阀、工艺流程阀门、换向阀门、反应堆阀门、流化床燃烧室阀门、高压气体反应器和降压装置等。 圆顶阀关闭时(图5),密封圈处于xx松弛(不充气)状态,阀瓣与阀座之间存在一定的间隙。阀瓣旋转,物料随着阀瓣的转动,有的穿过该间隙进入容器,有的停留在间隙处。当阀瓣旋转至关闭位置,密封圈开始充气膨胀,并紧紧裹住间隙里各种形状的颗粒附着在阀瓣的边缘,圆顶阀xx关闭。圆顶阀开启之前,密封圈先排气至xx松弛。阀瓣与阀座间恢复到原来的间隙,阀瓣开始转动至开位。 根据适用物料情况可选用带刮圈(清洁粘附在穹体表面的残余物料,用于粘性物料)或不带刮圈(适用于流动性好的物料)的圆顶阀。圆顶阀使用时必须检查所有紧固件,尤其确保阀内固定穹形体和轴的螺栓已紧固。圆顶阀开启或关闭时,两侧应无压差,否则压力高侧的气体和物料将高速穿过阀瓣和密封圈的间隙,造成阀瓣和密封圈磨损。可膨胀密封圈在阀门开启或关闭之前应该xx收缩,否则将造成阀瓣切割损坏密封圈。可膨胀密封圈的膨胀压力必须高于阀门的介质压力,否则密封圈将不xx膨胀,会导致密封圈和阀瓣之间产生空气及物料泄漏,会冲刷密封圈、阀瓣及其他部件。 圆顶阀由于其独特的结构和加工工艺,使其可在磨损、高温、腐蚀或粘性等特殊工况下连续稳定地运行,性能可靠,在正常使用工况下,每运转100万次才需要检修一次。密封圈是{wy}的磨损件。由于密封圈是一种柔性部件,位于托圈和顶盘之间,由紧固件固定,便于拆卸和检修。 根据适用物料情况可选用带刮圈(清洁粘附在穹体表面的残余物料,用于粘性物料)或不带刮圈(适用于流动性好的物料)的圆顶阀。圆顶阀使用时必须检查所有紧固件,尤其确保阀内固定穹形体和轴的螺栓已紧固。圆顶阀开启或关闭时,两侧应无压差,否则压力高侧的气体和物料将高速穿过阀瓣和密封圈的间隙,造成阀瓣和密封圈磨损。可膨胀密封圈在阀门开启或关闭之前应该xx收缩,否则将造成阀瓣切割损坏密封圈。可膨胀密封圈的膨胀压力必须高于阀门的介质压力,否则密封圈将不xx膨胀,会导致密封圈和阀瓣之间产生空气及物料泄漏,会冲刷密封圈、阀瓣及其他部件。 3.4、蝶阀 蝶阀(图6)具有结构简单,体积小,质量轻,材料耗用省,安装尺寸小,开关迅速,90°往复回转,驱动力矩小等特点,用于截断、接通和调节管路中的介质,具有良好的流体控制特性和关闭密封性能。 1.阀体2.闸板3.阀杆4.多层次密封圈5.填料6.支架7.电动装置 蝶板的流线形设计,使流体阻力变小,是一种节能型产品。随着耐高温、耐低温、耐强腐蚀、高强度合金材料在蝶阀中的应用,使金属密封蝶阀在高温、低温、强冲蚀等工况下得到广泛的应用,并部分取代了截止阀、闸阀和球阀。由于蝶阀蝶板的运动带有擦拭性,故大多数蝶阀可用于带悬浮颗粒的介质,依据密封件的强度也可用于粉状和颗粒状的介质,又能进行灵敏的流量控制,蝶阀的结构原理适合于制作大口径阀门。在要求节流和调节控制流量、泥浆介质及含固体颗粒介质、要求阀门结构长度短、要求启闭速度快和压差较小的工况条件下,推荐选用蝶阀。在双位调节、缩口的通道、低噪声、有气穴和气化现象、向大气少量渗漏及介质有磨损性时,可以选用蝶阀。在特殊工况条件下节流调节或要求密封严格,过磨损严重、低温(深冷)等工况条件下使用蝶阀时,应选用特殊设计金属密封带调节装置的三偏心或双偏心的专用蝶阀。 3.5、夹管阀 夹管阀有法兰和螺纹2种连接形式(图7)。DN10～50夹管阀可选用螺纹连接方式,DN40～250夹管阀可以选用法兰连接形式。夹管阀无阻碍流道,低流阻,无阻塞,{bfb}关断密封,低耗气量,质量轻,广泛应用于有颗粒、粉末、纤维、黏浆等磨损性物质的化工、纸浆、造纸、食品、电力、再循环、水处理和矿物加工等行业。夹管阀控制简单,比较经济,夹管更换方便,通常选用夹管阀作为排气用阀。由于夹管为橡胶制品,其耐磨和耐温性能均不及圆顶阀。可以根据不同的使用工况来选择排气阀,在使用温度不高,物料磨损性不强的情况下,选用夹管阀xxx较好。高温或物料磨损性较强的情况下,可选用闸阀、球阀、蝶阀、以及圆顶阀,但是球阀和蝶阀相对寿命较短,闸阀体积较大,动作不灵活,圆顶阀使用寿命最长,维护方便,只是价格较高,但总的xxx还是很好的。 3.6、直流式气动控制阀(角座阀) 角座阀(图8)常用规格为DN10～65,根据连接形式一般可分为螺纹和焊接式两种,根据控制形式可分为单作用角座阀和双作用角座阀。阀体材质为不锈钢,阀座密封材质主要为PTFE,适用介质为水、中性气体或液体、酒精、油、有机溶剂、水蒸汽、弱酸或弱碱溶液等,适用温度范围-100～180℃,适用压力范围为≤116MPa。在气力输送系统中一般选用螺纹连接的单作用角座阀。对于不同的输送系统可以根据需要选用。 4、结语 为了保证气力输送系统运行稳定,应合理选择阀门的类型,并做好维护保养工作。

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原文：
Pneumatic conveying is a compressed gas source for the transmission power, the powder material in a sealed container transport from one end to the other end. Pneumatic conveying is widely applied in industries such as coal power plants, fly ash and bottom slag, chemical industry, chemical raw materials, building industry, cement and lime, food and a variety of medical and health industries powder or granular material and so on. The rational use of various valves in the pneumatic conveying is essential. Valves to meet the needs of the pneumatic conveying industry, should have the temperature resistance, corrosion resistance and wear resistance and other aspects of good performance. 2, valve Categories Typical positive pressure pneumatic conveying system shown in Figure 1. Valve in the system according to the location and function, into the feed valves, exhaust valves, intake valves, discharge valves and switching valves and so on. 2.1 feed valves Feed valves in the pneumatic conveying of materials used to cut and connect to transport containers from the delivery point of the valve. Reasonable choice of the caliber of the feed valve determines the flow of materials and the whole system's capacity. Different according to the medium, its temperature, corrosion and wear resistance are also different levels of requirements. According to experience, in different systems is usually valve, ball valve, valve dome used as feed valve. 2.2, exhaust valves Exhaust valves when feeding pneumatic conveying systems, it will be discharged to the air transport system into the hopper or stack of valves in order to facilitate smooth feeding, reduce the feeding time. The main transmission medium is air with a small amount of powder material. Common exhaust valve are gate valve, butterfly valve, clamp control valve, ball valve and the dome valve. 2.3, intake valves Often the intake valves are butterfly valve, ball valve, angle seat valve. Inlet valves of the transport medium for the compressed air, so do not ask abrasion resistance. 2.4, a material with a valve When the conveyor is full of material, the open inlet valve and outlet valve, so that materials in the compressed air driven transportation system in the pipeline. Therefore, the media outlet valve for the powder material mixed with compressed air. As the outlet valve of the valve generally gate valve, ball valve, dome valve. 2.5, splitter valves Shunt valve can play the role of segregation and convergence, the material from the collection of more material to the point or to spread from one point to multiple points. As a shunt valve with ball valve, butterfly valve, or combination, but also the manufacturers made the shunt valve. Shunt valve for pipeline installation can also be used for library roof installation. Generally used for library roof installation, the valve need to connect the entrance elbow, libraries need to install a small top discharging position to properly channel the expansion material to reduce dust Ash. 3, valve performance 3.1, valve Valve (Figure 2) has two gate to cut off the material, gate material can choose stainless steel or alloy steel, to apply anti-corrosion and wear-resistant conditions. Valve with manual, pneumatic and electric three kinds of mode of operation. Usually use two kinds of pneumatic or electric control means. However, due to the reasons for its structure, gate of the trip is longer, pneumatic or electrical devices on the torque requirement and motion a long cycle, use is not flexible enough. Pneumatic cylinder valve is driven open or closed gate valve, T-shaped gate seat with the special structure of linear motion in the gate while driving along the center of circular rotation of the valve seat sealing surface to play a certain self- grinding and polishing cleaning, helped seal gate materials to withstand the impact of uniform circumference and wear, to avoid the gate in the long run the process locally damaged or worn out, so life is greatly extended. Meanwhile, the double plate in the spring under the static pressure on both sides to ensure the seal does not leak, when the ram pressure on one side, the other side of the role of energy through the spring and sealing seat closer contact to achieve the sealing effect. The valve in use is sealed and the main problems of erosion damage to gate. The valve is suitable for fully open or fully closed in the state of work, if the gate a long time in a semi-switch mode of operation the sealing surface of gate dielectric due to erosion will become imprecise. Therefore, the valves in the anti-erosion and abrasion areas should be further improved. 3.2 Ball Ball valve (Figure 3) is usually selected automatically (pneumatic or electric) control valve. Ball valve with soft seal and seal 2. Soft sealing valve of the valve seat seal material is PTFE, which has a friction coefficient is small, stable, easy to aging and excellent sealing characteristics. Because PTFE has a high expansion coefficient, the sensitivity of the cold and poor thermal conductivity, when the sealing material hardens, the seal of reliability to be affected. Furthermore, the PTFE low temperature levels, only the circumstances under which less than 180 ℃. Over this temperature, seal materials will soften. When the long-term use, the temperature generally should be controlled below 120 ℃. Ball Valve inlet valve is generally used as the medium temperature higher power plant ash handling systems, pneumatic conveying systems are often as 24h continuous, relatively high frequency of valve movement, generally a few minutes short of even tens of seconds will move one. If the service life of Ball Valve 2 to 3 million, assuming that the pneumatic conveying system, the valve action time 5min, then the ball of the service life of 70 to 104 days, shorter service life of the valve. Therefore, in power plant ash handling system, the need for longer service life of the hard seal ball valve. 3.3, the dome valve Dome valve (Figure 4) because of its unique structure, usually the first choice for pneumatic conveying valve. Dome shell and the domed valve disc material often used in cast iron, stainless steel, special wear-resistant materials and steel fluorine plastics. Seal materials are often used in rubber, silicone rubber, fluorine rubber and EPDM rubber. Dome valve is tightly sealed to rely on compressed air to achieve special effects valves for gas processing dust, erosion of bulk materials, such as for the library / store discharge valve, flow valve, gate valve, valve reactors, fluidized bed combustion chamber valves, high pressure gas reactor and step-down devices. Dome valve closure (Fig. 5), ring in the fully relaxed (not inflated) state, the valve flap and valve seat gap exists between. Disc rotation, the material with the disc rotation, some through the gap into the container, and some remain in the interstices. When the valve flap rotation to the closed position, seals began to inflate, and wrapped tightly in space of particles of various shapes attached to the edge of the disc, dome valve is completely closed. Dome valve is opened before the exhaust to completely seal the first relaxation. Valve flap and seat back to the original gap between the valve flap began to turn to the open position. Situation can be used in accordance with applicable material with scraper ring (clean adhesion surface in the dome of residual materials, for viscous materials) or without scraping ring (for good mobility materials) of the dome valve. Dome valve used to check all fasteners, in particular, to ensure that the valve body and the axis fixed dome bolts are tightened. Dome valve open or closed, both sides should be no pressure difference, or the high pressure side of the gas and the materials and high-speed through the valve flap seals the gap, causing the valve flap and seal wear. Expandable ring before the opening or closing the valve should be fully contracted, or will cause disc damage the seal cutting. The expansion of inflatable seals pressure must be higher than the medium pressure valve, or seals will not be fully expanded, would lead to ring and disc leakage between the air and materials will be washed seals, valves, valve and other components. Dome valve because of its unique structure and processing technology, it can wear, high temperature, corrosion or other special condition viscous continuous and stable operation, reliable performance, under normal use condition, each operation needs one million times before maintenance time. Ring is the only wear parts. As the ring is a flexible component, located between the Loop and the top plate, fixed by the fasteners for easy removal and maintenance. Situation can be used in accordance with applicable material with scraper ring (clean adhesion surface in the dome of residual materials, for viscous materials) or without scraping ring (for good mobility materials) of the dome valve. Dome valve used to check all fasteners, in particular to ensure that the valve body and the axis fixed dome bolts are tightened. Dome valve open or closed, both sides should be no pressure difference, or the high pressure side of the gas and the materials and high-speed through the valve flap seals the gap, causing the valve flap and seal wear. Inflatable seals in the valve should be completely opened or closed before the contract, otherwise it will damage the seals causing the valve flap cut. The expansion of inflatable seals pressure must be higher than the medium pressure valve, or seals will not be fully expanded, would lead to ring and disc leakage between the air and materials will be washed seals, valves, valve and other components. 3.4, butterfly valve Valve (Figure 6) has a simple structure, small size, light weight, material consumption province, installation, small size, fast switching, 90 ° reciprocating rotation, torque and small features, for truncation, connect and adjust the pipe The media has a good flow control characteristics and close sealing performance. 1. Body 2. Ram 3. Stem 4. Multi-layered seal ring 5. Packing 6. Stent 7. Electric devices The streamline design of the disc, the fluid resistance becomes smaller, a energy-efficient products. With the high temperature, low temperature, resistant to corrosion, high strength alloy materials in the butterfly valve application, the metal sealing butterfly valve in the high-temperature, low temperature, strong erosion and other widely used condition, and partially replaced the cut-off valves, gate valves and ball valves. As the valve disc with the wipe of the movement, so most of the butterfly valve can be used with suspended particles of the medium, based on the strength of seals can also be used in powder and granular media, but also for sensitive flow control, butterfly valve structure principle for the production of large diameter valves. Control the throttle and adjust the required flow of mud media and media containing solid particles require shorter length of the valve structure to require opening and closing speed and less pressure working conditions, the recommended use butterfly. In the double-digit adjusted, reduced channel, low noise, there is the phenomenon of cavitation and gasification, a small amount of leakage to the atmosphere and the media have to wear, you can use butterfly. In the special working conditions or requirements under the throttle closed strict regulation, had worn a serious, low-temperature (cryogenic) and other working conditions when the use of butterfly valves, metal seals should be used with a specially designed three eccentric adjustment device or a special double eccentric butterfly. 3.5, clip tube valve Clip flange and threaded pipe valve has two kinds of connection forms (Figure 7). DN10 ~ 50 folders can be used threaded pipe valve connection, DN40 ~ 250 clip flange pipe valve can be selected form. Folder unimpeded flow control valves, low flow resistance, non-blocking, {bfb} sealed off, low air consumption, light weight, widely used in a particle, powder, fiber, pulp and other sticky substances wear chemical, pulp, building paper, food, electricity, recycling, water treatment and mineral processing industries. Folder control valve control is simple, economical, easy to change folders pipe, usually used as the exhaust pipe valve folder Valves. As the clip tube for the rubber, the wear and heat resistance, and not the dome valve. According to different conditions used to select the exhaust valve, the temperature is not high, the material wear resistance is not strong cases, pipe valves cost-effective use folders better. High temperature or abrasive materials strong case can be selected gate valve, ball valve, butterfly valve, and the dome valve, but relatively short-lived ball and butterfly valves, gate valves larger, action is not flexible, dome maximum valve life, easy maintenance, just higher prices, but the overall cost is still very good. 3.6, DC-pneumatic control valve (angle seat valve) Angle seat valve (Figure 8) Common specifications for the DN10 ~ 65, according to the form of connection can be separated into two threads and welding, according to the role of forms of control can be divided into single-and double-action angle seat valve angle seat valve. Body made of stainless steel, valve seat seal material is mainly PTFE, for medium to water, neutral gases or liquids, alcohol, oil, organic solvents, water vapor, such as weak acid or alkaline solution, temperature range -100 ~ 180 ℃ applied pressure range ≤ 116MPa. In pneumatic conveying systems generally use a single threaded connection the role of angle seat valve. For different delivery systems can use as needed. 4 Conclusion To ensure stable operation of pneumatic conveying system, the type of valve should be properly chosen, and do maintenance work.